Structural biology of the multidrug and toxic compound extrusion superfamily transporters

Xenobiotic and metabolite extrusion is an important process for the proper functions of cells and their compartments, including acidic organelles. MATE (multidrug and toxic compound extrusion) is a large family of secondary active transporters involved in the transport of various compounds across cellular and organellar membranes, and is present in the three domains of life. The major substrates of the bacterial MATE transporters are cationic compounds, including clinically important antibiotics, and thereby MATE transporters confer multidrug resistance to pathogenic bacteria. The plant MATE transporters are important for the accumulation of various metabolites in organelles, including vacuoles. The human MATE transporters are expressed in the brush-border membrane of the kidney, and are involved in the clearance of cationic drugs from the body. During the past decade, progress in structural biology has clarified the transport mechanism of these MATE transporters in atomic detail. The present review summarizes the reported structures of MATE family transporters, along with their structure-guided functional analyses. This integrated view of the structures of MATE transporters provides novel insights into their transport mechanism.